Alpha-olefins are made in commercial quantities by a process developed in the fifties by Karl Ziegler and his coworkers. The so-called Ziegler process involves the reaction of triethyl aluminum (TEA) and ethylene at temperatures in the range of 200.degree.-350.degree. F. and pressure in the range of 2000-5000 psig to yield a mixture of tri-C.sub.2-20+ alkyl aluminum having a poisson distribution and C.sub.2-20 olefins. The ethylene is flashed from the reaction mixture for recycle and the light olefins through 1-decene can be distilled from the mixed aluminum alkyls since they have a normal boiling point below the lightest aluminum alkyl (viz. TEA). In the past, attempts to distill 1-dodecene and 1-tetradecene from the mixed aluminum alkyls resulted in a substantial amount of the TEA and other light aluminum alkyls co-distilling with the 1-dodecene and 1-tetradecene. This light aluminum alkyl represents an economic penalty because it must be hydrolyzed which also serves to contaminate the .alpha.-olefin product with paraffins, e.g. ethane, butane and hexane.
This problem was recognized in Roming et al. U.S. Pat. No. 3,227,773 wherein the patentees state:
"Some prior art processes have been limited generally to the production of C.sub.8-10 olefins, since no practical methods were known for completely separating olefins boiling close to C.sub.10-14 olefins from the C.sub.2 or C.sub.3 alkyl aluminum remaining after the displacement reaction. Thus, the C.sub.12 and higher olefins could not be economically distilled overhead from the liquid alkyl aluminum due to the relatively low decomposition temperature of said alkyl aluminum and/or the closely similar boiling ranges of lower alkyl aluminum and these higher olefins."
From this it is apparent that a need exists for an efficient method of separating C.sub.12-14 .alpha.-olefins from aluminum alkyls containing light alkyls such as TEA. It is an object of the present invention to provide such a method.